如何用开关语句和扫描实用程序模拟商店队列？

Question

我必须使用scan、switch和cases制作一个Java程序，在这些程序中，我可以使用命令“add”添加一个客户，使用命令“remove”删除一个客户。

队列中的默认客户数为5。如果客户数量超过8，则打印“此队列太大”如果少于1名客户，则打印“队列中无人”

我试图做一些代码，但我不知道下一步该做什么。

import java.util.Scanner;

public class fronta {
    public static void main(String[] args) {
    
    System.out.println ("This queue has 5 people in it at the moment.");    
    Scanner scan = new Scanner(System.in);
    boolean x = true;
    String b = "ADD";
    int a = 5;
    b = scan.nextLine();
    while(x){
    switch (b) {
    case "ADD":
        
    System.out.println ("This queue has " + a + " people in it at the moment.");
    b = scan.nextLine();
    System.out.println ("This queue is too big");
        break;
    
    default:
    case "EXIT":
        System.out.println("End of simulation.");
        x = false;
        break;  
   }
  }
 }
}

Answer 1

我想你需要一些像下面这样的东西：

public static void main(String[] args) {
    boolean isExitRequested = false;
    int queueSize = 5;
    System.out.println ("This queue has "+queueSize+" people in it at the moment.");
    Scanner scan = new Scanner(System.in);

    while(scan.hasNextLine()){
        String input = scan.nextLine();
        switch (input){
            case "ADD":
                System.out.println ("This queue has " + queueSize++ + " people in it at the moment.");
                if (queueSize > 8) {
                    System.out.println("This queue is too big");
                }
                break;
            case "REMOVE":
                if (queueSize == 0){
                    System.out.println("There's nobody in the queue.");
                } else {
                    queueSize--;
                }
                break;
            case "EXIT":
                isExitRequested = true;
                break;
            default:
                System.out.println("Unknown input: "+input);
        }

        if(isExitRequested)
            break;
    }

}